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cold; short; curt; blunt
彼女の素っ気ない返事に内心ひどく傷ついてしまった。
I was deeply hurt inside by her curt reply.
受付の対応がとても素っ気なかった。
The response at the reception desk was very curt.
彼女は見た目ほど素っ気なくない。
She is not as cold as she appears.